1. Technical Field
Embodiments disclosed herein relate to the field of switch circuits for use in programmable gain amplifiers. More particularly, embodiments of the present disclosure relate to programmable gain amplifiers that may handle high input swing signals, including negative voltages.
2. Description of Related Art
In current technological applications of programmable gain amplifiers (PGAs), such as in power meters and temperature sensors, a high input voltage swing is becoming a common occurrence. Generally, a closed loop PGA including operational amplifiers (op-amps), switches and resistors has been employed to handle this high input voltage swing. The switches are used to select the gain level desired for a certain input signal. Linearity of the response of the PGA device is desired in order to keep the appropriate performance over a wide range of input values. In most cases, switches used in the prior art are transistor-based devices that may not be able to turn completely ‘off’ due to leakage currents within the transistors. The inability of some of the switches to turn ‘off’ in some cases may lead to a nonlinear response of the amplifier, especially when a high input swing is being received.
What is needed is a switch circuit that may turn completely ‘off’ for a wide input voltage swing in a programmable gain amplifier, including negative voltages.